Devices are known that are capable of detecting the presence of the moving element in a gearchanger system in one or another of its predetermined positions corresponding to selecting and changing gear, for example in systems of the clutch-by-wire type in which a clutch is controlled by an actuator, itself controlled by data processor means on the basis of detecting positions in which a gearchange lever is placed by the driver of the vehicle.
Nevertheless, those prior art devices are not capable, in general, of continuously detecting the transmission ratio that is engaged in the vehicle gearbox, even though such information could be used for various purposes by computer processor means, e.g. for reducing fuel consumption and/or the emission of polluting compounds into the atmosphere, or even for preventing starting the engine when a gear is engaged.
It is also important for this information to be obtained using a minimum number of detector components and in a manner that is as inexpensive as possible.